8,898 research outputs found
A chemical evolution model for galaxy clusters
We develop a toy-model for the chemical evolution of the intracluster medium,
polluted by the galactic winds from elliptical galaxies. The model follows the
"galaxy formation history" of cluster galaxies, constrained by the observed
luminosity function.Comment: 6 pages, 10 figures, to appear in the Proceedings of the Workshop
"Chemical Enrichment of Intracluster and Intergalactic Medium", Vulcano,
Italy, 14-18 May 2001, ASP Conference Serie
Green public procurement criteria for road infrastructures: State of the art and proposal of a weighted sum multicriteria analysis to assessenvironmental impacts
In the last years, the attention to environmental issue is growing, demonstrating the interest to protect the nature and to better use the non-renewable resources. At international level, and especially in the European Community, for different trades, a wide production of voluntary documents and institutional acts proves the interest and the need for a green economy. An innovative approach may lead to the experience of Green Public Procurements (GPP), to protect the environment as a public interest and to promote technological developments. So far, the experiences of GPP are limited, not entirely positive and in the field of road infrastructures almost entirely absent. Construction and maintenance of road infrastructures is objectively more complex than purchasing goods or services. The paper proposes the integration of the weighted sum multi-criteria analysis into existing procedures. The methodology needs for environmental labels related to materials, machines and works which contribute to the final product "road". The labels are recognized at international level and consistent with procedures, conditions and criteria currently published in road tenders, therefore the approach can be followed to pursue the environmental sustainability of road infrastructures without compromising the economic attention
Strong and Electro-Weak Supersymmetric Corrections to Single Top Processes at the Large Hadron Collider
We present the one-loop corrections originating from Quantum Chromo-Dynamics
(QCD) and Electro-Weak (EW) interactions of Supersymmetric (SUSY) origin within
the Minimal Supersymmetric Standard Model (MSSM) to the single-top processes bq
-> tq' and qbar q' -> tbar b. We illustrate their impact onto top quark
observables accessible at the Large Hadron Collider (LHC) in the 't+jet' final
state, such as total cross section, several differential distributions and
left-right plus forward-backward asymmetries. We find that in many instances
these effects can be observable for planned LHC energies and luminosities,
quite large as well as rather sensitive to several MSSM parameters.Comment: 22 pages, 10 figures; added a brief comment on the dependence of
results on the value of top mass; corrected typo
Tree Level Unitarity Bounds for the Minimal B-L Model
We have derived the unitarity bounds in the high energy limit for the minimal
B-L extension of the Standard Model by analysing the full class of Higgs and
would-be Goldstone boson two-to-two scatterings at tree level. Moreover, we
have investigated how these limits could vary at some lower critical value of
the energy.Comment: 20 pages, 4 figures, 2 tables; 1d figure modified, typos corrected,
bibliography augmented; published in PRD after minor adjustmen
The Z' boson of the minimal B-L model at future Linear Colliders in e+e- --> mu+mu-
We study the capabilities of future electron-positron Linear Colliders, with
centre-of-mass energy at the TeV scale, in accessing the parameter space of a
boson within the minimal model. We carry out a detailed comparison
between the discovery regions mapped over a two-dimensional configuration space
( mass and coupling) at the Large Hadron Collider and possible future
Linear Colliders for the case of di-muon production. As known in the literature
for other models, we confirm that leptonic machines, as compared to the
CERN hadronic accelerator, display an additional potential in discovering a
boson as well as in allowing one to study its properties at a level of
precision well beyond that of any of the existing colliders.Comment: 5 pages, proceeding of LC09 (Perugia), published by the Italian
Physical Society in the Nuovo Cimento C (Colloquia
Designable buried waveguides in sapphire by proton implantation
Buried and stacked planar as well as buried single and parallel channel waveguides are fabricated in sapphire by proton implantation. Good control of the implantation parameters provides excellent confinement of the guided light in each structure. Low propagation losses are obtained in fundamental-mode, buried channel waveguides without postimplantation annealing. Choice of the implantation parameters allows one to design mode shapes with different ellipticity and/or mode asymmetry in each orthogonal direction, thus demonstrating the versatility of the fabrication method. Horizontal and vertical parallelization is demonstrated for the design of one- or two-dimensional waveguide arrays in hard crystalline materials
Photonic band gaps analysis of Thue-Morse multilayers made of porous silicon
Dielectric aperiodic Thue-Morse structures up to 128 layers have
been fabricated by using porous silicon technology. The photonic band gap
properties of Thue-Morse multilayers have been theoretically investigated
by means of the transfer matrix method and the integrated density of states.
The theoretical approach has been compared and discussed with the
reflectivity measurements at variable angles for both the transverse electric
and transverse magnetic polarizations of light. The photonic band gap
regions, wide 70 nm and 90 nm, included between 0 and 30°, have been
observed for the sixth and seventh orders, respectively
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